Field of the Invention
The present invention relates to a method for acquiring SiC plates by slicing an ingot made of SiC.
Description of the Related Art
A cylindrical or prismatic ingot is sliced into a plurality of plate-shaped workpieces. One way to slice an ingot into plate-shaped workpieces is to use a wire saw. For example, when an ingot made of a material such as silicon or glass is cut into individual plate-shaped workpieces using a wire saw, the kerf loss caused by a wire saw (width of the portion removed by the wire saw) amounts to 100 μm to 150 μm. Therefore, a method has been proposed which positions the focal point of a laser beam inside an ingot and scans the focal point, in order to reduce the width of the kerf loss, so as to slice the ingot into plate-shaped workpieces (refer, for example, to Japanese Patent Laid-Open No. 2005-277136).
Here, if the ingot is made of silicon or glass as described above, the area machined with a laser beam, i.e., the sliced cross-section, is machined to a mirror-finished surface. Therefore, laser machining and slicing step are conducted repeatedly to acquire plate-shaped workpieces from an ingot. Laser machining is designed to form a separation layer inside the ingot. Slicing step is designed to slice the ingot into plate-shaped workpieces starting from the separation layer.